Is this a good alternator???

[i12flytoday]

This is my first post, but I have benefited the huge wealth of experience on this forum. Thanks ahead for any help you may be able to give.

I have a Wellcraft with a 1982 Mercruiser 228 with the #1 outdrive. I'm in the process of adding 2 search lights and a bunch of LED's as well as a DVD / LCD setup in a modified pelican case in the cabin. To run all of this I will be adding two house batteries, or 4 if I go with the golf cart type setup that I have been considering. I'm quite mechanically inclined and can fabricate brackets and work out a different size belt if needed.

Anyway, the point is, will this alternator fit a Marine application?

http://cgi.ebay.com/ebaymotors/CHRO...R-140-AMP_W0QQitemZ160259927015QQcmdZViewItem

I have been reading about spark shields and such, and I cannot tell in the pictures if this alternator qualifies.

Also, would it be better to just add another alternator, say a duplicate 55A, and only wire that to charge the house battery and keep it a separate system?

Any help you can give is appreciated.

Wade

P.S. I have no idea who the seller in that ad is, I was just pointing out one that I thought might work based on an ebay search.

 

[dlplost]

Re: Is this a good alternator???

NO, it's NOT a marine alt, don't use it.

Just how many amps you planning to use?
search lights are the only load I see in what you are doing, LED's don't draw hardly any power unless you have hundreds of them, DVD / LCD are both low power devices.

If you have a 55a alt now, I would expect it to run all that. Even Aircraft landing lights only draw about 16a each so 2 of them would only be 32a. Just how BIG are these lights you planning to use?

I would keep your current alt, add a batt isolator and a second bank of 1 or 2 batts for the house

 

[Silvertip]

Re: Is this a good alternator???

This alternator is not shielded. Marine applications require shielded alternators to avoid sparks from igniting engine bay fumes. As mentioned, DO NOT use it.

 

[i12flytoday]

Re: Is this a good alternator???

Ok, thanks... Actually, the problem is that my current alternator definitely doesn't put out enough power. When moving slowly with the lights on (100W each), when I turn both lights on, they dim and my nav lights and dash lights dim. I'm looking at a 68 amp currently that is a marine alt for sure. I don't know if my alt is just on its last leg due to age, probably (its a 1982 original), or if I'm just drawing too much power for too little RPMs. Maybe a combination of both. LOL

Anyway, I'm thinking I will just replace it with the larger alt and see what happens. Thanks for the help though.

 

[Boatist]

Re: Is this a good alternator???

2 100 watt lights should draw about 17 amps. At trolling speed your alternator may not put out that much but you can tell by watching the volt meter. It the voltage is above 12.6 volts then the alternator is supplying enough power to runn the lights. 13.8 volts is enough to run the lights and charge your battery.

Check the Alternator Belt and make sure it is in the top of the pulley not down at the bottom where it will slip. Also make sure it tight.
If it slips it will put out a lot less current when it has a load.
Also if you know how open up the alternator and check the slip rings brushes.
While you have it open check all the screens to make sure they are in place and clean so air can get thru to keep it cool.

 

[bruceb58]

Re: Is this a good alternator???

Another option is to put a smaller pulley on it so that it will spin faster if you are predominately at low RPMs.

 

[ftltony]

Re: Is this a good alternator???

Another option is to put a smaller pulley on it so that it will spin faster if you are predominately at low RPMs.

Not always a good idea. the faster is spins, the shorter the life.

 

[bruceb58]

Re: Is this a good alternator???

Very true...especially in an automotive application. Automotive is low RPMs too but many many more hours. Sounds like this poster needs it for low RPMs so the tradeoff may be worth it.

 

[jlinder]

Re: Is this a good alternator???

You need to measure the voltage at the battery at low speed with the lights on. What is the voltage?

If the lights dim it might be voltage drop in the wires, not the charging voltage.